While the number of diagnostic technologies available for adult applications continues to grow, there remains a paucity of technologies suitable for fetal evaluation. In particular, noninvasive assessment of fetal electrophysiology has not been routinely possible. In the last few years, however, we and other groups have demonstrated the efficacy of fetal magnetocardiography (fMCG) as a new method of evaluating fetal arrhythmia, including its ability to provide critical information unavailable from ultrasound. Building on this success, we propose here to develop techniques to further improve the signal resolution of fMCG and to extend its applicability to other patient populations, including fetuses with congenital heart disease and increased risk of heart failure and sudden death. The two main goals of the research are: 1) to improve the efficacy of fMCG as a diagnostic tool for fetal rhythm assessment by investigating new signal processing methods to increase the resolution of fMCG waveform components and the signal detection rate at early gestational ages. This will be accomplished by: "implementing independent component analysis (ICA) algorithms to separate the fetal signal from maternal and environmental interference " developing new methods of computing fetal heart rate tracings and estimating the spatiotemporal characteristics of the fMCG, based on the concept of particle filtering " utilizing ultrasound imaging to estimate an fMCG forward solution that can be used to develop a data- independent beamformer 2) to identify magnetophysiological markers associated with suboptimal outcome in fetuses with arrhythmia, congenital heart disease, hydrops, and other high-risk conditions. This will be accomplished by: developing techniques to improve the detection accuracy of T-wave abnormalities, including "microvolt-T-wave alternans" correlating ominous heart rate and rhythm patterns, such as T-wave alternans, PR- and ST-segment shifts, nonreactivity, and low heart rate variability, with outcome in various high-risk pregnancy conditions. The goals of the research are 1) to develop new techniques to improve the efficacy of fetal magnetocardiography as a diagnostic tool for assessment of fetuses with arrhythmia, congenital heart disease, hydrops, and other high-risk conditions, and 2) to identify magnetophysiological markers associated with suboptimal outcome and risk of sudden fetal demise.